Studying the Dynamics of Ligand–Receptor Complexes by Single-Molecule Techniques - Single Molecule Dynamics in Life Science - page 139

Table 7.1 Single-molecule experiments investigating ligand binding and receptor diffusion in living cells.

Receptor Ligand Technique Receptor mobility and ligand binding properties Reference

GPCR
A1-AR

in CHO cells Antagonist xanthine amine FCS Diffusion: One population of slow-diffusing receptor-bound

ligands was observed.

[139]

congener labeledwith Bodipy

630 Binding: The uorescent competitive antagonist binds to

the intramembrane region of A1-AR. Binding isotherms
yield K d ¼ 33 nM and B max ¼ 75 nM.

N 6 -aminobutyl adenosine la-
beled with Bodipy 630

A1-AR in CHO cells FCS Diffusion: Two populations of ligand - receptor complexes

with different mobility were observed.

[140]

b 2 -AR in hippocampal neurons

and alveolar epithelial type II
cell line A549

Arterenol labeled with Alexa FCS Diffusion: Two populations of ligand receptor complexes

with different mobility were observed. The fast-diffusion
component appears immediately after ligand addition,
whereas the slow-diffusing component is delayed, which is
likely due to the internalization of ligand

[141]

-

532

receptor

-

complexes.

Binding: Equilibrium and kinetic experiments revealed
K d ¼ 10 8 M 1 s 1 in 1.3 nM, B max ¼ 6.0 nM, and k ass ¼ 4.9 ·

neurons, and K d ¼ 6.0 nM, B max ¼ 15.1 nM, and k ass ¼ 1.2

· 10 8 M 1 s 1 in A549 cells.

(Continued)